S. Sakanaka et T. Obina, Observation of longitudinal quadrupole-mode oscillations of a bunch which were induced by RF phase modulation in the electron storage ring, JPN J A P 1, 40(4A), 2001, pp. 2465-2474
It has been reported that the beam lifetime in electron storage rings can b
e improved by applying a small phase modulation on the rf accelerating volt
age at a frequency of two-times the synchrotron oscillation frequency. This
effect can be explained as being due to the improved Touschek lifetime tha
t is caused by an excited bunch-shape oscillation in the stored bunches. In
order to understand this phenomenon further, we investigated the induced b
unch-shape oscillation in the 2.5-GeV Photon Factory storage ring at High E
nergy Accelerator Research Organization (KEK). Using both a streak camera a
nd a spectrum analyzer, we observed the quadrupole-mode oscillations of a s
tored single bunch very clearly. It showed a splitting of a single bunch in
to three or two bunchlets, which depended on the modulation frequency. We r
eport on these experimental results, and discuss them using computer simula
tions and an analytical formalism.